The invention relates to a process for detecting the catalytic activity of solid materials in which process one or more starting materials are brought to reaction in the presence of the solid materials.
These processes have the disadvantages that large amounts of substances and, due to serial testing, much time for repeating steps are required. In the course of what is termed xe2x80x9ccombinatorial chemistryxe2x80x9d, libraries of substances are prepared, many substances being synthesized simultaneously, albeit in small amounts (P. G. Schultz et al., Science 1995, 1738; Michael J. Natan, J. Am. Chem. Soc. 118, 1996, 8721-8722).
The object underlying the invention was therefore to provide a process which succeeds with smaller amounts of substance than hitherto for a pure activity screening and permits more rapid examination of the solid materials.
This object is achieved by a process of the type mentioned at the outset, which is characterized in that the solid materials are present, spatially separated from one another, on a support, in that the starting materials are brought into contact with the solid materials and in that the resultant product or products are analyzed by a mass spectrometer, with resolution of location regarding the solid materials on the support.
The invention therefore relates to a process for detecting the catalytic activity of solid materials, in which process one or more starting materials are brought to reaction in the presence of the solid materials, characterized in that the solid materials are present, spatially separated from one another, on a support, in that the starting materials are brought into contact with the solid materials and in that the resultant product or products are analyzed by a mass spectrometer, with resolution of location regarding the solid materials on the support.
According to the invention, a mass spectrometer is used for the analysis. Mass spectrometers permit analysis down to a few molecules, and substance mixtures and isotope mixtures may also be analyzed directly.
A first preferred embodiment of the invention is characterized in that a plurality of solid materials, preferably more than 20, very particularly preferably more than 100, are present, separated from one another, on a support and as a result can be examined simultaneously. In a second preferred embodiment, the solid materials can be heated or cooled.
A further preferred embodiment is that the mass spectrometer is a TOF (time of flight) mass spectrometer (arrangement as described by W. C. Wiley and I. H. McLaren Rev. Sci. Instr. 26, 12 1955, 1150-1157). Preferably, for the analysis with the mass spectrometer, a Multi-Channel-Plate (MCP) detector can be used, particularly preferably a location-resolving MCP detector (MCP array with phosphor screen or fluorescent screen), since then the reactions at different positions of the abovementioned support can be analyzed simultaneously. In a further preferred embodiment of the invention, the reaction is carried out in a first vacuum chamber and the analysis in a second vacuum chamber, the two chambers being separated by an orifice plate. This permits the support to have an increased streaming rate, in order to be quite sure that sufficient starting material can be brought into contact with the solid material without increasing the spectroscopic background too greatly due to gas feed. In the analytical compartment or reaction compartment, a pressure xe2x89xa610xe2x88x925 mbar, particularly preferably xe2x89xa610xe2x88x926 mbar, very particularly preferably xe2x89xa610xe2x88x927 mbar, can be set using vacuum pumps. In the reaction compartment, the true pressure immediately over the solid materials can depart from vacuum up to atmospheric pressure depending on the streaming. Solid starting materials or starting materials having a particularly low vapor pressure can also be brought into contact with the potentially catalytically active solid material directly prior to evacuation of the system by single application termed batch processes by those skilled in the art.
A further preferred embodiment is characterized in that the individual solid material or individual solid materials are present in an amount less than 1 mg, preferably less than 0.1 mg, particularly preferably less than 0.01 mg, very particularly preferably less than 0.001 mg. This permits activity screening of the substance libraries (pools) which are known from the literature and mentioned at the outset.
As additional embodiments of the analysis, a device for focusing the molecular beam can also be used, in order to permit, for example in a location-resolving detector, the assignment of the reaction products to the individual support positions (solid materials) by the orifice plate. A further additional embodiment is a low-fragmentation ionization of the products by laser pulse (T. Baumert, J. L. Herek, A. H. Zeweil J. Chem. Phys, 99(6), 1993, 4430-4440), which prevents product molecules from breaking down into lighter fragments before they reach the detector and thus falsifying the product analysis.
The advantages of the process according to the invention are essentially that a rapid serial or parallel detection of the catalytic activity of solid materials with very small amounts under identical conditions is now possible.
To carry out the processes according to the invention, an apparatus is particularly suitable which comprises one or more vacuum chambers, a catalyst support and a mass spectrometer. An apparatus is further particularly suitable which is the subject matter of the invention, having a vacuum chamber on which a mass spectrometer is arranged and which has at least one inlet for gas, characterized in that the inlet or each inlet is designed as a support for solid materials and has at least one capillary, the number of the capillaries being able to be any integer from 1 to at least 100.
A first particular design of this apparatus is characterized in that the capillary or each capillary has a diameter from the range 5 to 100, preferably 10 to 50, xcexcm. With a suitable selection of diameter and length of the capillary (capillaries), the gas can be passed onto the solid materials even at atmospheric pressure and even at superatmospheric pressure (greater than 1 bar absolute).
A second particular design of this apparatus is characterized in that the support or each support has the shape of a plate and is inclined to the detector part of the mass spectrometer at an angle of 30 to 60xc2x0, preferably 45xc2x0.